The United Nations humanitarian chief said Wednesday that Syria’s eastern Aleppo has essentially become a “kill zone” with more than 400 people slain and nearly 2,000 wounded in the past month.

“So many of them, too many of them, were children,” Stephen O’Brien told the U.N. Security Council in his monthly report on the organization’s ability to get humanitarian assistance to residents of the war-torn country.

“At the very minimum, I call upon all council members who have operational military assets in Syria to take concrete steps to halt the aerial bombardment of civilian areas,” O’Brien said.

He repeated accusations that the U.N. secretary-general and the high commissioner for human rights have made, that the Syrian government and Russia are responsible for the most sustained and intensive aerial bombardment campaign since the beginning of the conflict nearly six years ago.

Last week, Syria and Russia began a brief unilateral pause in the bombing over eastern Aleppo for the evacuation of the critically ill and injured, and so aid workers could get humanitarian supplies into that part of the city, which has not had an aid delivery in nearly four months. It was extended for eight days, but because security was not guaranteed by all parties, the humanitarian teams could not carry out their mission.

“There will be complaints and accusations about who caused the failure of the medical evacuations,” O’Brien said. “And yes, they will finger point at the U.N., the one party in all this not to blame, to attempt to divert blame from the perpetrators and refusers.”

This is a translation provided to VOA but not independently verified of a leaflet allegedly dropped on Aleppo, Syria, Oct. 26, 2016. It reads: Read … and Repeat … This is your last hope … Save yourselves. If you do not leave these areas urgently, you will be annihilated. … We have opened for you a safe passage to exit. … Make a quick decision: save yourselves. … You know that everyone has given up on you. … They left you alone to face your doom and nobody will give you any help.

‘Save yourselves’

The frustrated humanitarian chief said there are fewer than 30 doctors left in eastern Aleppo, which still has more than 250,000 residents, and only six partially functioning hospitals. He said only 11 working ambulances remain, and the shortage of blankets is so acute that patients are using body bags for warmth.

“Let me be clear: eastern Aleppo is besieged by the Syrian government,” O’Brien said. He criticized the “medieval tactics” of the regime and its Russian allies, such as dropping leaflets from aircraft over neighborhoods warning residents, “This is your last hope … save yourselves.” The threat is that if the residents do not leave, they will be “annihilated.”

Russia’s envoy, Vitaly Churkin, denied that his government’s air force was responsible for dropping the leaflets, saying they had “not been within 10 kilometers of eastern Aleppo in eight days.” He suggested that U.S. aircraft might have been responsible, or that the “save yourselves” warning was from fake leaflets that circulated on the internet.

“Russia can’t have it both ways: to pretend to care about the well-being of people of eastern Aleppo, and at the same time to threaten to annihilate those who remain in their homes,” U.S. Ambassador to the U.N. Samantha Power said.

Council members also expressed shock at the attack earlier Wednesday on a school in Idlib. Twenty-two children and six teachers were reportedly killed. If the school was deliberately targeted it would constitute a war crime.

Map showing control areas around the Syrain city of Aleppo, as of Oct. 13, 2016

Bearing responsibility

O’Brien laid the blame for lack of action to stop the bloodletting in Syria at the door of the Security Council.

“This council has been charged with the responsibility for ending this horror,” he said. “The buck stops with you.”

Russia has used its veto five times to stop council action against its ally Syria during the course of the conflict.

Last week the General Assembly discussed the possibility of invoking a rarely used mechanism that would allow it to circumvent the council if it is at a dangerous impasse.